Simultaneous spin-coating and solvent annealing: manipulating the active layer morphology to a power conversion efficiency of 9.6% in polymer solar cells†
We developed a simultaneous spin-coating/solvent-annealing process and demonstrated morphology optimization for PTB7 based organic photovoltaics. This novel processing method enhances the edge-on crystalline content in thin films and induces the formation of weak PCBM aggregates. As a result, the efficiency of polymer solar cells increased from 9.2% to a certified high efficiency of 9.61%, owing to an enhanced short-circuit current (Jsc, 18.4 mA cm−2vs. 17. 5 mA cm−2) and an improved fill factor.